High prevalence of human anti-mouse antibodies in the serum of colorectal cancer patients.

BACKGROUND Monoclonal antibody treatment induces the expression of human anti-mouse antibodies (HAMA), which in turn interfere with the therapy. However, whether HAMAs are expressed before the initiation of antibody therapy in patients with colorectal cancer remains unknown. MATERIALS AND METHODS Serum samples were collected from 40 patients diagnosed with colorectal cancer. Serum samples from 157 individuals without cancer were used as controls. None of the patients received imaging or therapeutic antibodies before the study. The expression of HAMAs was evaluated by ELISA with murine immunoglobulin G1 (mIgG)1, mIgG2a and mIgG2b as the antigen. RESULTS Of the 40 colorectal cancer patients, 9 (22.5%) expressed either IgG- or IgM-type HAMAs while only 13/157 (8.2%) of the individuals without cancer expressed the HAMAs (p<0.05). CONCLUSION HAMAs are prevalent in the serum of colorectal cancer patients even before antibody administration. Medical practitioners should be alert to the possibility of HAMA expression when administering antibody therapy.